Had Sonny defeated Cassius Clay in May 1965, there was no place to go.

Sonny was also banned from fighting in Canada, so a George Chuvalo
bout was impossible.

Yeah, and the Las Vegas casinos (who were connected to Sonny Liston) would have made some big money as fight fans passed through.
It's hard to say how much, but by the 1980s the casinos were paying the promoters to bring fights to them (rather than the promoters hiring the venue), so the receipts must be significant.